Question

Which curve is tighter (has a shorter radius)?

a) A 3-degree curve (any definition)

b) A 3.5-degree curve (arc definition)

c) A 4-degree curve (chord definition)

Answer 1

Ans a) By arc defination,

100/D = 2R/360

where, D = Curve degree

R = Curve radius

Putting values,

=> (100/3) = 2R / 360

=> R = 360 x 100 / (3 x 2)

=> R = 1910.8 ft

Ans b) By arc defination,

100/D = 2R/360

where, D = Curve degree

R = Curve radius

Putting values,

=> (100/3.5) = 2R / 360

=> R = 360 x 100 / (3.5 x 2)

=> R = 1637.85 ft

Ans c) By chord defination,

Sin(D/2) = 50/R

where, D = Curve degree

R = Curve radius

Putting values,

=> Sin (4/2)  = 50/R

=> 0.03489 = 50/R

=> R = 1432.68 ft

Since, part (c) has lowest radius , tighter curve is 4 degree curve (chord definition)